C++ DatumGetUInt32函数代码示例

/*
 * Construct a jsonb_ops GIN key from a flag byte and a textual representation
 * (which need not be null-terminated).  This function is responsible
 * for hashing overlength text representations; it will add the
 * JGINFLAG_HASHED bit to the flag value if it does that.
 */
static Datum
make_text_key(char flag, const char *str, int len)
{
	text	   *item;
	char		hashbuf[10];

	if (len > JGIN_MAXLENGTH)
	{
		uint32		hashval;

		hashval = DatumGetUInt32(hash_any((const unsigned char *) str, len));
		snprintf(hashbuf, sizeof(hashbuf), "%08x", hashval);
		str = hashbuf;
		len = 8;
		flag |= JGINFLAG_HASHED;
	}

	/*
	 * Now build the text Datum.  For simplicity we build a 4-byte-header
	 * varlena text Datum here, but we expect it will get converted to short
	 * header format when stored in the index.
	 */
	item = (text *) palloc(VARHDRSZ + len + 1);
	SET_VARSIZE(item, VARHDRSZ + len + 1);

	*VARDATA(item) = flag;

	memcpy(VARDATA(item) + 1, str, len);

	return PointerGetDatum(item);
}

static uint32
build_hash_key(const void *key, Size keysize __attribute__((unused)))
{
    Assert(key);

    BMBuildHashKey *keyData = (BMBuildHashKey*)key;
	Datum *k = keyData->attributeValueArr;
	bool *isNull = keyData->isNullArr;

	int i;
	uint32 hashkey = 0;

	for(i = 0; i < cur_bmbuild->natts; i++)
	{
		/* rotate hashkey left 1 bit at each step */
		hashkey = (hashkey << 1) | ((hashkey & 0x80000000) ? 1 : 0);

        if ( isNull[i] && cur_bmbuild->hash_func_is_strict[i])
        {
            /* leave hashkey unmodified, equivalent to hashcode 0 */
        }
        else
        {
            hashkey ^= DatumGetUInt32(FunctionCall1(&cur_bmbuild->hash_funcs[i], k[i]));
        }

	}
	return hashkey;
}

/*
 * Add a resource to ResourceArray
 *
 * Caller must have previously done ResourceArrayEnlarge()
 */
static void
ResourceArrayAdd(ResourceArray *resarr, Datum value)
{
	uint32		idx;

	Assert(value != resarr->invalidval);
	Assert(resarr->nitems < resarr->maxitems);

	if (RESARRAY_IS_ARRAY(resarr))
	{
		/* Append to linear array. */
		idx = resarr->nitems;
	}
	else
	{
		/* Insert into first free slot at or after hash location. */
		uint32		mask = resarr->capacity - 1;

		idx = DatumGetUInt32(hash_any((void *) &value, sizeof(value))) & mask;
		for (;;)
		{
			if (resarr->itemsarr[idx] == resarr->invalidval)
				break;
			idx = (idx + 1) & mask;
		}
	}
	resarr->lastidx = idx;
	resarr->itemsarr[idx] = value;
	resarr->nitems++;
}

uint32
mcxt_ptr_hash_std(const void *key, Size keysize)
{
    uint32 hashval;
    hashval = DatumGetUInt32(hash_any(key, keysize));
    return hashval;
}

/*
 *		CatalogCacheComputeHashValue
 *
 * Compute the hash value associated with a given set of lookup keys
 */
static uint32
CatalogCacheComputeHashValue(CatCache *cache, int nkeys, ScanKey cur_skey)
{
	uint32		hashValue = 0;
	uint32		oneHash;

	CACHE4_elog(DEBUG2, "CatalogCacheComputeHashValue %s %d %p",
				cache->cc_relname,
				nkeys,
				cache);

	switch (nkeys)
	{
		case 4:
			oneHash =
				DatumGetUInt32(DirectFunctionCall1(cache->cc_hashfunc[3],
												   cur_skey[3].sk_argument));
			hashValue ^= oneHash << 24;
			hashValue ^= oneHash >> 8;
			/* FALLTHROUGH */
		case 3:
			oneHash =
				DatumGetUInt32(DirectFunctionCall1(cache->cc_hashfunc[2],
												   cur_skey[2].sk_argument));
			hashValue ^= oneHash << 16;
			hashValue ^= oneHash >> 16;
			/* FALLTHROUGH */
		case 2:
			oneHash =
				DatumGetUInt32(DirectFunctionCall1(cache->cc_hashfunc[1],
												   cur_skey[1].sk_argument));
			hashValue ^= oneHash << 8;
			hashValue ^= oneHash >> 24;
			/* FALLTHROUGH */
		case 1:
			oneHash =
				DatumGetUInt32(DirectFunctionCall1(cache->cc_hashfunc[0],
												   cur_skey[0].sk_argument));
			hashValue ^= oneHash;
			break;
		default:
			elog(FATAL, "wrong number of hash keys: %d", nkeys);
			break;
	}

	return hashValue;
}

/*
 * Remove a resource from ResourceArray
 *
 * Returns true on success, false if resource was not found.
 *
 * Note: if same resource ID appears more than once, one instance is removed.
 */
static bool
ResourceArrayRemove(ResourceArray *resarr, Datum value)
{
	uint32		i,
				idx,
				lastidx = resarr->lastidx;

	Assert(value != resarr->invalidval);

	/* Search through all items, but try lastidx first. */
	if (RESARRAY_IS_ARRAY(resarr))
	{
		if (lastidx < resarr->nitems &&
			resarr->itemsarr[lastidx] == value)
		{
			resarr->itemsarr[lastidx] = resarr->itemsarr[resarr->nitems - 1];
			resarr->nitems--;
			/* Update lastidx to make reverse-order removals fast. */
			resarr->lastidx = resarr->nitems - 1;
			return true;
		}
		for (i = 0; i < resarr->nitems; i++)
		{
			if (resarr->itemsarr[i] == value)
			{
				resarr->itemsarr[i] = resarr->itemsarr[resarr->nitems - 1];
				resarr->nitems--;
				/* Update lastidx to make reverse-order removals fast. */
				resarr->lastidx = resarr->nitems - 1;
				return true;
			}
		}
	}
	else
	{
		uint32		mask = resarr->capacity - 1;

		if (lastidx < resarr->capacity &&
			resarr->itemsarr[lastidx] == value)
		{
			resarr->itemsarr[lastidx] = resarr->invalidval;
			resarr->nitems--;
			return true;
		}
		idx = DatumGetUInt32(hash_any((void *) &value, sizeof(value))) & mask;
		for (i = 0; i < resarr->capacity; i++)
		{
			if (resarr->itemsarr[idx] == value)
			{
				resarr->itemsarr[idx] = resarr->invalidval;
				resarr->nitems--;
				return true;
			}
			idx = (idx + 1) & mask;
		}
	}

	return false;
}

/*
 * Compute the hash value for a tuple
 *
 * The passed-in key is a pointer to TupleHashEntryData.  In an actual hash
 * table entry, the firstTuple field points to a tuple (in MinimalTuple
 * format).  LookupTupleHashEntry sets up a dummy TupleHashEntryData with a
 * NULL firstTuple field --- that cues us to look at the inputslot instead.
 * This convention avoids the need to materialize virtual input tuples unless
 * they actually need to get copied into the table.
 *
 * Also, the caller must select an appropriate memory context for running
 * the hash functions. (dynahash.c doesn't change CurrentMemoryContext.)
 */
static uint32
TupleHashTableHash(struct tuplehash_hash *tb, const MinimalTuple tuple)
{
	TupleHashTable hashtable = (TupleHashTable) tb->private_data;
	int			numCols = hashtable->numCols;
	AttrNumber *keyColIdx = hashtable->keyColIdx;
	uint32		hashkey = hashtable->hash_iv;
	TupleTableSlot *slot;
	FmgrInfo   *hashfunctions;
	int			i;

	if (tuple == NULL)
	{
		/* Process the current input tuple for the table */
		slot = hashtable->inputslot;
		hashfunctions = hashtable->in_hash_funcs;
	}
	else
	{
		/*
		 * Process a tuple already stored in the table.
		 *
		 * (this case never actually occurs due to the way simplehash.h is
		 * used, as the hash-value is stored in the entries)
		 */
		slot = hashtable->tableslot;
		ExecStoreMinimalTuple(tuple, slot, false);
		hashfunctions = hashtable->tab_hash_funcs;
	}

	for (i = 0; i < numCols; i++)
	{
		AttrNumber	att = keyColIdx[i];
		Datum		attr;
		bool		isNull;

		/* rotate hashkey left 1 bit at each step */
		hashkey = (hashkey << 1) | ((hashkey & 0x80000000) ? 1 : 0);

		attr = slot_getattr(slot, att, &isNull);

		if (!isNull)			/* treat nulls as having hash key 0 */
		{
			uint32		hkey;

			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i],
												attr));
			hashkey ^= hkey;
		}
	}

	/*
	 * The way hashes are combined above, among each other and with the IV,
	 * doesn't lead to good bit perturbation. As the IV's goal is to lead to
	 * achieve that, perform a round of hashing of the combined hash -
	 * resulting in near perfect perturbation.
	 */
	return murmurhash32(hashkey);
}

/*
 * Hash functions for lexemes. They are strings, but not NULL terminated,
 * so we need a special hash function.
 */
static uint32
lexeme_hash(const void *key, Size keysize)
{
	const LexemeHashKey *l = (const LexemeHashKey *) key;

	return DatumGetUInt32(hash_any((const unsigned char *) l->lexeme,
								   l->length));
}

/*
 * Hash function for elements.
 *
 * We use the element type's default hash opclass, and the default collation
 * if the type is collation-sensitive.
 */
static uint32
element_hash(const void *key, Size keysize)
{
	Datum		d = *((const Datum *) key);
	Datum		h;

	h = FunctionCall1Coll(array_extra_data->hash, DEFAULT_COLLATION_OID, d);
	return DatumGetUInt32(h);
}

/*
 * _hash_datum2hashkey -- given a Datum, call the index's hash procedure
 *
 * The Datum is assumed to be of the index's column type, so we can use the
 * "primary" hash procedure that's tracked for us by the generic index code.
 */
uint32
_hash_datum2hashkey(Relation rel, Datum key)
{
	FmgrInfo   *procinfo;

	/* XXX assumes index has only one attribute */
	procinfo = index_getprocinfo(rel, 1, HASHPROC);

	return DatumGetUInt32(FunctionCall1(procinfo, key));
}

/*
 * Calculate hash value for a key
 */
static uint32
pgss_hash_fn(const void *key, Size keysize)
{
	const pgssHashKey *k = (const pgssHashKey *) key;

	/* we don't bother to include encoding in the hash */
	return hash_uint32((uint32) k->userid) ^
		hash_uint32((uint32) k->dbid) ^
		DatumGetUInt32(hash_any((const unsigned char *) k->query_ptr,
								k->query_len));
}

/*
 * _hash_datum2hashkey -- given a Datum, call the index's hash procedure
 *
 * The Datum is assumed to be of the index's column type, so we can use the
 * "primary" hash procedure that's tracked for us by the generic index code.
 */
uint32
_hash_datum2hashkey(Relation rel, Datum key)
{
	FmgrInfo   *procinfo;
	Oid			collation;

	/* XXX assumes index has only one attribute */
	procinfo = index_getprocinfo(rel, 1, HASHPROC);
	collation = rel->rd_indcollation[0];

	return DatumGetUInt32(FunctionCall1Coll(procinfo, collation, key));
}

/*
 * Compute the hash value for a tuple
 *
 * The passed-in key is a pointer to TupleHashEntryData.  In an actual hash
 * table entry, the firstTuple field points to a tuple (in MinimalTuple
 * format).  LookupTupleHashEntry sets up a dummy TupleHashEntryData with a
 * NULL firstTuple field --- that cues us to look at the inputslot instead.
 * This convention avoids the need to materialize virtual input tuples unless
 * they actually need to get copied into the table.
 *
 * Also, the caller must select an appropriate memory context for running
 * the hash functions. (dynahash.c doesn't change CurrentMemoryContext.)
 */
static uint32
TupleHashTableHash(struct tuplehash_hash *tb, const MinimalTuple tuple)
{
	TupleHashTable hashtable = (TupleHashTable) tb->private_data;
	int			numCols = hashtable->numCols;
	AttrNumber *keyColIdx = hashtable->keyColIdx;
	uint32		hashkey = hashtable->hash_iv;
	TupleTableSlot *slot;
	FmgrInfo   *hashfunctions;
	int			i;

	if (tuple == NULL)
	{
		/* Process the current input tuple for the table */
		slot = hashtable->inputslot;
		hashfunctions = hashtable->in_hash_funcs;
	}
	else
	{
		/*
		 * Process a tuple already stored in the table.
		 *
		 * (this case never actually occurs due to the way simplehash.h is
		 * used, as the hash-value is stored in the entries)
		 */
		slot = hashtable->tableslot;
		ExecStoreMinimalTuple(tuple, slot, false);
		hashfunctions = hashtable->tab_hash_funcs;
	}

	for (i = 0; i < numCols; i++)
	{
		AttrNumber	att = keyColIdx[i];
		Datum		attr;
		bool		isNull;

		/* rotate hashkey left 1 bit at each step */
		hashkey = (hashkey << 1) | ((hashkey & 0x80000000) ? 1 : 0);

		attr = slot_getattr(slot, att, &isNull);

		if (!isNull)			/* treat nulls as having hash key 0 */
		{
			uint32		hkey;

			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i],
												attr));
			hashkey ^= hkey;
		}
	}

	return hashkey;
}

/*
 * string_hash: hash function for keys that are null-terminated strings.
 *
 * NOTE: this is the default hash function if none is specified.
 */
uint32
string_hash(const void *key, Size keysize)
{
	/*
	 * If the string exceeds keysize-1 bytes, we want to hash only that many,
	 * because when it is copied into the hash table it will be truncated at
	 * that length.
	 */
	Size		s_len = strlen((const char *) key);

	s_len = Min(s_len, keysize - 1);
	return DatumGetUInt32(hash_any((const unsigned char *) key,
								   (int) s_len));
}

/*
 * Compute the hash value for a tuple
 *
 * The passed-in key is a pointer to TupleHashEntryData.  In an actual hash
 * table entry, the firstTuple field points to a tuple (in MinimalTuple
 * format).  LookupTupleHashEntry sets up a dummy TupleHashEntryData with a
 * NULL firstTuple field --- that cues us to look at the inputslot instead.
 * This convention avoids the need to materialize virtual input tuples unless
 * they actually need to get copied into the table.
 *
 * CurTupleHashTable must be set before calling this, since dynahash.c
 * doesn't provide any API that would let us get at the hashtable otherwise.
 *
 * Also, the caller must select an appropriate memory context for running
 * the hash functions. (dynahash.c doesn't change CurrentMemoryContext.)
 */
static uint32
TupleHashTableHash(const void *key, Size keysize)
{
	MinimalTuple tuple = ((const TupleHashEntryData *) key)->firstTuple;
	TupleTableSlot *slot;
	TupleHashTable hashtable = CurTupleHashTable;
	int			numCols = hashtable->numCols;
	AttrNumber *keyColIdx = hashtable->keyColIdx;
	FmgrInfo   *hashfunctions;
	uint32		hashkey = 0;
	int			i;

	if (tuple == NULL)
	{
		/* Process the current input tuple for the table */
		slot = hashtable->inputslot;
		hashfunctions = hashtable->in_hash_funcs;
	}
	else
	{
		/* Process a tuple already stored in the table */
		/* (this case never actually occurs in current dynahash.c code) */
		slot = hashtable->tableslot;
		ExecStoreMinimalTuple(tuple, slot, false);
		hashfunctions = hashtable->tab_hash_funcs;
	}

	for (i = 0; i < numCols; i++)
	{
		AttrNumber	att = keyColIdx[i];
		Datum		attr;
		bool		isNull;

		/* rotate hashkey left 1 bit at each step */
		hashkey = (hashkey << 1) | ((hashkey & 0x80000000) ? 1 : 0);

		attr = slot_getattr(slot, att, &isNull);

		if (!isNull)			/* treat nulls as having hash key 0 */
		{
			uint32		hkey;

			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i],
												attr));
			hashkey ^= hkey;
		}
	}

	return hashkey;
}